Fluid flow valves which include air release or air purge features are well known. These valves are generally located within liquid conduits and are designed to insure the continuous release of air or other gases to avoid air locks which otherwise interfere with the flow of liquid through the conduit. So-called combination valves are also known which also function to purge air from the conduit on start-up and to provide vacuum relief upon system shut down. These valves incorporate a flexible valve seal assembly connected to a float which rises and falls within the valve body to open and close the valve in a predetermined manner to achieve the three functions stated above.
One known combination air release valve construction is disclosed in U.S. Pat. No. 4,770,201. Others are disclosed in commonly owned U.S. Pat. Nos. 5,794,646 and 5,957,150, and in pending application Ser. No. 09/288,858, now U.S. Pat. No. 6,145,533, the latter incorporated herein by reference. While the valves disclosed in the commonly owned patents, and particularly in the '858 application have performed fairly well, a problem has been encountered in that the small and large apertures in the valve seat are separated by a "wall" or "partition" which some times results in the smaller aperture becoming clogged. This, in turn, can result in a continuously leaking valve.